Cypriot leaders pursuing a historic accord to reunify their island were joined by the foreign ministers of Greece, Turkey and Britain on Thursday, with talks expected to turn to the security arrangements needed to end four decades of ethnic division.

The three so-called guarantor nations took part in negotiations at the United Nations in Geneva, where Greek- and Turkish-Cypriot officials have been meeting since Jan. 9 to narrow their differences. Chief among the disputes is the issue of how each community will be protected within the proposed federal state. Britain is present as it ruled Cyprus until its independence in 1960, and has military bases there.

A negotiated outcome to one of the world’s toughest diplomatic challenges would be welcomed in a Europe convulsed by a surge of anti-establishment politics, and as violence roils EU aspirant Turkey and the nearby Middle East. But earlier hopes that this week’s discussions would cap 19 months of diplomacy with a final, binding pact appeared to be receding. An outline agreement followed by further talks is seen as the most likely outcome.

“We are working hard to have a settlement that addresses the central questions that have been discussed for a long time” involving territory, property and relations with the EU, UN Secretary General Antonio Guterres said in Geneva. “It is my hope that there will be a breakthrough,” he said. “I strongly believe that Cyprus can be the symbol of hope at the beginning of 2017.”

‘Liability’

Greek Prime Minister Alexis Tsipras says his country is willing to give up its protector status, and Greek Cypriots say that such powers wouldn’t be needed in a unified Cyprus that’s a member of the EU. Turkey, which maintains tens of thousands of troops on the island, aims to keep its guarantor role to safeguard Turkish Cypriots, a minority of about one-fifth of the island’s population whose self-proclaimed state is only recognized by Ankara.

The gap between Turkey and other parties on a security framework is one obstacle to a deal, according to Mujtaba Rahman, analyst at London-based Eurasia Group. For Turkish President Recep Tayyip Erdogan, who wants nationalist backing for his push to concentrate more powers in his office, “any kind of concession on its current Cyprus policy would be a liability.”

Given the state of the region, the security guarantees that have underpinned stability in Cyprus for 43 years are “a necessity,” Turkish Foreign Minister Mevlut Cavusoglu said. “We expect this issue to be discussed in line with the realities on the island.”

Cyprus has been divided since a Turkish invasion in 1974 triggered by a coup aimed at uniting the island with Greece. As many as 150,000 Greek Cypriots were forced south, and about 50,000 Turkish Cypriots fled north. All had to leave behind personal property, another sticking point in the talks.

Cyprus President Nicos Anastasiades and Turkish-Cypriot leader Mustafa Akinci on Wednesday put forward their respective plans for delineating territory in the federation.

Guterres chaired Thursday’s opening session, his first international meeting since taking up the role on Jan. 1. He was joined by Greek Foreign Minister Nikos Kotzias, Cavusoglu and British Foreign Secretary Boris Johnson. European Commission President Jean-Claude Juncker is representing the EU.

Economic Boost

Any final accord would need to be approved by separate referendums in the north and south of the island. “This will be an agreement to be ratified by peoples,” Guterres said, “and you know, looking at what’s happening in the world, that referenda are not an easy challenge.”

A settlement would offer economic as well as political benefits. Because it’s so close to the Turkish coast, a deal would allow the export of eastern Mediterranean oil and gas to Turkish markets and Europe via a pipeline from Cyprus.

Almost nine in 10 Turkish Cypriots want Turkey to stay as a guarantor of their rights under a deal, according to a survey by Turkey’s Gezici polling company, which interviewed 1,300 people in mid-December. Just over 75 percent said EU membership for a federal state wouldn’t safeguard their security.

This week “might be treated as a station before the last station,” Ahmet Sozen, research director of the Nicosia-based Center for Sustainable Peace and Democratic Development, said in Geneva Thursday. “Day-to-day security concerns of the people cannot be fixed by the presence of Turkish or Greek troops, or the intervention rights of guarantor powers. You need special mechanisms of the federal institution to address those.”